// Copyright (c) 2013 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "net/spdy/spdy_read_queue.h"

#include <algorithm>
#include <cstddef>
#include <memory>
#include <string>

#include "base/stl_util.h"
#include "net/spdy/spdy_buffer.h"
#include "testing/gtest/include/gtest/gtest.h"

namespace net {

namespace {

    const char kData[] = "SPDY read queue test data.\0Some more data.";
    const size_t kDataSize = arraysize(kData);

    // Enqueues |data| onto |queue| in chunks of at most |max_buffer_size|
    // bytes.
    void EnqueueString(const std::string& data,
        size_t max_buffer_size,
        SpdyReadQueue* queue)
    {
        ASSERT_GT(data.size(), 0u);
        ASSERT_GT(max_buffer_size, 0u);
        size_t old_total_size = queue->GetTotalSize();
        for (size_t i = 0; i < data.size();) {
            size_t buffer_size = std::min(data.size() - i, max_buffer_size);
            queue->Enqueue(std::unique_ptr<SpdyBuffer>(
                new SpdyBuffer(data.data() + i, buffer_size)));
            i += buffer_size;
            EXPECT_FALSE(queue->IsEmpty());
            EXPECT_EQ(old_total_size + i, queue->GetTotalSize());
        }
    }

    // Dequeues all bytes in |queue| in chunks of at most
    // |max_buffer_size| bytes and returns the data as a string.
    std::string DrainToString(size_t max_buffer_size, SpdyReadQueue* queue)
    {
        std::string data;

        // Pad the buffer so we can detect out-of-bound writes.
        size_t padding = std::max(static_cast<size_t>(4096), queue->GetTotalSize());
        size_t buffer_size_with_padding = padding + max_buffer_size + padding;
        std::unique_ptr<char[]> buffer(new char[buffer_size_with_padding]);
        std::memset(buffer.get(), 0, buffer_size_with_padding);
        char* buffer_data = buffer.get() + padding;

        while (!queue->IsEmpty()) {
            size_t old_total_size = queue->GetTotalSize();
            EXPECT_GT(old_total_size, 0u);
            size_t dequeued_bytes = queue->Dequeue(buffer_data, max_buffer_size);

            // Make sure |queue| doesn't write past either end of its given
            // boundaries.
            for (int i = 1; i <= static_cast<int>(padding); ++i) {
                EXPECT_EQ('\0', buffer_data[-i]) << -i;
            }
            for (size_t i = 0; i < padding; ++i) {
                EXPECT_EQ('\0', buffer_data[max_buffer_size + i]) << i;
            }

            data.append(buffer_data, dequeued_bytes);
            EXPECT_EQ(dequeued_bytes, std::min(max_buffer_size, dequeued_bytes));
            EXPECT_EQ(queue->GetTotalSize(), old_total_size - dequeued_bytes);
        }
        EXPECT_TRUE(queue->IsEmpty());
        return data;
    }

    // Enqueue a test string with the given enqueue/dequeue max buffer
    // sizes.
    void RunEnqueueDequeueTest(size_t enqueue_max_buffer_size,
        size_t dequeue_max_buffer_size)
    {
        std::string data(kData, kDataSize);
        SpdyReadQueue read_queue;
        EnqueueString(data, enqueue_max_buffer_size, &read_queue);
        const std::string& drained_data = DrainToString(dequeue_max_buffer_size, &read_queue);
        EXPECT_EQ(data, drained_data);
    }

    class SpdyReadQueueTest : public ::testing::Test {
    };

    // Call RunEnqueueDequeueTest() with various buffer size combinatinos.

    TEST_F(SpdyReadQueueTest, LargeEnqueueAndDequeueBuffers)
    {
        RunEnqueueDequeueTest(2 * kDataSize, 2 * kDataSize);
    }

    TEST_F(SpdyReadQueueTest, OneByteEnqueueAndDequeueBuffers)
    {
        RunEnqueueDequeueTest(1, 1);
    }

    TEST_F(SpdyReadQueueTest, CoprimeBufferSizes)
    {
        RunEnqueueDequeueTest(2, 3);
        RunEnqueueDequeueTest(3, 2);
    }

} // namespace

} // namespace net
